Pole mechanism for double-throw pressure contact switch

ABSTRACT

A pole mechanism for a double-throw pressure contact switch comprising a V-shaped movable contact member pivotally mounted on a center terminal, the two blades of the movable contact member being engageable with respective end terminals. A unified actuating means, comprising a main actuating lever and two sets of overcenter biased toggle linkages, is employed to throw the switch and to clamp the blades to the switch terminals whenever the switch is fully thrown. The motion of the actuating lever is along a simple, continuous path. Each toggle linkage includes a lost-motion connection to permit effective operation of the blade clamps by one linkage without breaking the other toggle.

United States Patent Sterne 1 1 Feb.29,19'72 [72] Inventor: Manfred Stene, Chicago, 111.

Erickson Chicago, 111

[22] Filed: Aug. 27, 1970 [21] Appl. No.: 67,524

[73] Assignee: Electrical Equipment Co.,

Wescoat ..200/5 R Kussmaul.... ..200/162 Primary Examiner-4, V. Truhe Assistant Examiner-Gale R. Peterson Att0rneyKinzer, Dorn and Zickert [57] ABSTRACT A pole mechanism for a double-throw pressure contact switch comprising a V-shaped movable contact member pivotally mounted on a center terminal, the two blades of the movable contact member being engageable with respective end terminals. A unified actuating means, comprising a main actuating lever and two sets of overcenter biased toggle linkages. is employed to throw the switch and to clamp the blades to the switch terminals whenever the switch is fully thrown The motion of the actuating lever is along a simple, continuous path. Each toggle linkage includes a lostmoti0n connection to permit effective operation of the blade clamps by one linkage without breaking the other toggle.

6 Claims, 4 Drawing Figures Patented Feb. 29, 1972 3 Sheets-Sheet l FIG] INVENTOR MANFRED STENE Q ZM K ZTTORNEYS Patented Feb. 29, 1972 3,646,299

3 Sheets-Sheet 2 PIC-3.2

INVENTOR MANFRED STENE BY KWVQMWZM ATTORNFYS Patented Feb. 29, 1972 3 Sheets-Sheet 3 INVENTOR MANFRED STENE ATTORNEYS IOLE MECHANISM FOR DOUBLE-THROW PRESSURE CONTACT SWITCH BACKGROUND OF THE INVENTION Double-throw switches are among the oldest of electrical devices. In one known structural variation, each pole ofa double-throw switch comprises a V-shaped movable contact member that has its apex mounted upon a center terminal and that can be pivoted to connect the center terminal to either one of two linearly aligned end terminals. This mechanism is rather versatile; for example, by increasing the angle of the V to greater than 90, with appropriately dimensioned end terminals, the switch can be constructed as a make-before-break device, With a narrow V, full clearance from one end terminal can be assured before contact is made with the other end terminal. affording a break-before-make switch. A typical example of a switch of this kind, with makebefore-break contacts, is disclosed in Wescoat US. Pat. No. 1,465,384.

In many applications requiring the switching of relatively high currents, particularly in service entrance equipment and in industrial applications, it is highly desirable that the switching apparatus include means for positively clamping the switch blades to the switch terminals. Bolted pressure contact switches have frequently been used in these applications. Often, such pressure contact switches use-s a toggle mechanism as a part of the actuating means that positively clamps the movable switch contact to the fixed terminals when the switch is closed.

However. conventional toggle mechanisms are not readily applicable to a double-throw switch pole that employs a unitary shaped movable contact to complete a circuit from a center terminal to either one oftwo end terminals. The actuating means for the switch must be capable of moving the main contact through a substantial arc in order to complete either ofthe two alternate circuits for the switch; it must also provide some auxiliary movement for clamping the movable contact of the switch to its fixed terminals. A toggle mechanism that functions in the usual manner, maintaining an actuating lever or other actuating means in fixed relation to the movable contact of the switch except when the switch is closed in one direction, interferes with closing of the switch in the opposite direction. Thus, double-throw switch mechanism affording clamped or other pressure contacts have often required rather complex movement of the actuating means in order to complete the throwing of the switch. As examples, reference may be made to Caswell US. Pat. No. 2,547,153, for which a relatively complex shifting movement of the movable contact is required, or to Graybill US. Pat. No. 2,456,520, in which the movable contact not only rotates about its longitudinal axis but also pivots about an entirely different axis in the course ofmovement from one closed position to another.

SUMMARY OF THE INVENTION It is a principal object ofthe present invention, therefore, to rovide a new and improved pole mechanism for a doubleihrow pressure contact switch of the kind that utilizes a V- shapcd movable contact member. mounted upon a center terminal and movable to connect that center terminal to either of two aligned end terminals.

Another object of the invention is to provide a new and improved double-throw pressure contact switch mechanism of the kind utilizing a V-shaped blade mounted on a center terminal and engageable with either oftwo aligned end terminals, that employs a single main actuating member movable over a simple continuous path from one fully closed position to the other fully closed position for the switch.

A further object ofthe invention is to provide a new and improved double-throw pressure contact switch mechanism, using a 'v'-shaped blade to connect a center fixed terminal with either of two end terminals, that incorporates two springbiased toggle mechanisms to lock an actuator member in a fixed position between the arms ofthe V-shaped movable contact when the switch is open and that also serve to actuate LAND clamping devices that clamp the moveable contact to the fixed terminals of the switch upon closing of the switch in either direction.

A pole mechanism for a double-throw pressure contact switch constructed in accordance with the invention comprises a center terminal mounted in aligned relation between first and second end terminals. A movable contact member, comprising first and second contact blades disposed in V configuration, has its apex mounted on the center terminal for pivotal movement between a first contact position in which its first blade engages the first end terminal and a second contact position in which its second blade engages the second end ter minal. The mechanism includes first and second clamp means for clamping the first and second contact blades to the first and second end terminals, respectively, as well as center clamp means for clamping the apex of the movable contact member to the center terminal. Each of these clamp means is actuatable between a released condition and a clamping con dition. The pole mechanism includes a unified actuating means for moving the movable contact member between its contact positions and for actuating the first clamp means and the center clamp means to clamping condition when the movable contact is in its first contact position; this actuating meansalso actuates the second clamp means and the center clamp means to clamping condition when the movable contact member is in its second contact position. The actuating means comprises a main actuating member movable along a simple continuous path from a first closed position to a second closed position to complete the full range of operations for the ac tuating means and hence for the pole mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side elevation view of a pole mechanism for a double-throw pressure contact switch constructed in accordance with one embodiment of the present invention, the switch being shown approaching a first closed condition;

FIG. 2 illustrates the pole mechanism of FIG. 1 in its first closed condition;

fig. 3 is a sectional view taken approximately along line 3 3 in FIG. 2; and

FIG. 4 is an elevation view of the pole mechanism showing the pole mechanism in a second closed position.

DESCRIPTION OF THE PREFERRED EMBODIMENT The pole mechanism I0 illustrated in the drawings comprises a typical embodiment of the present invention. Although only the single pole mechanism 10 is shown. it will be understood that the pole mechanism is usually combined with one, two or three additional substantially identical pole mechanisms in a complete switch apparatus. Pole mechanism 10 can be connected to and operated simultaneously with virtually any desired additional number of corresponding pole mechanisms, as will be apparent from the description set forth hereinafter.

Pole mechanism 10 is shown mounted upon a vertical insu lator base 11. The pole mechanism includes a fixed center terminal I2 mounted at the center of base 11. A first end ter minal I3 is mounted on base ll below center terminal I2. A second end terminal 14 is mounted on base 11 below center terminal 12, the three fixed terminals 12, I3 and I4 being aligned in a linear array. Each of terminals 12, I3 and 14 includes a fiat mounting element that is affixed to base 11 by suitable bolts or other mounting means and a contact portion that extends horizontally outwardly from the base. The first end terminal 13 is provided with a relatively large horizontal slot 15, as shown in FIGS. 1 and 4. The second end terminal 14 is of similar configuration and includes a relatively large horizontal slot 16 (FIG. 1).

Pole mechanism 10 further comprises a movable contact member 17. The movable contact member I7 includes first and second contact blades 21 and 22 arranged in a V-shaped configuration. The apex of the movable contact member I7 is mounted upon the center terminal 12 of the pole mechanism for pivotal movement between a first contact position in which the first blade 21 engages the first end terminal 13 (FIG. 2) and a second contact position in which the second blade 22 engages the second end terminal 14 (FIG. 4). Movable contact member 17, in the illustrated embodiment, is of split construction, so that each of the contact blades 21 and 22 is a dual blade that embraces the fixed terminals of the switch, as best shown in FIG. 3.

Pole mechanism is provided with a first clamping means 23 for clamping the two halves of the dual first contact blade 21 to the first end terminal 13. This first clamping means 23 comprises a clamp bolt 24 that extends through blade 22; the head of bolt 24 is located on the near side of blade 21 as seen in FIGS. 1, 2 and 4. Bolt 24 is threaded into a nut 25 mounted on the opposite side of blade 21 (FIG. 3). The angular orientation of nut 25, on blade 21, is determined by and fixed by a set screw dog 26 (FIG. 3). A protective sleeve 27 is mounted on the portion of clamp bolt 24 that extends between the two halves of the dual blade 21, but the length of sleeve 27 is short enough to permit firm clamping of contact blade 21 to terminal 13 by tightening of bolt 24 in nut 25.

A second clamp means 29 is provided for clamping the second contact blade 22 to the second end terminal 14 of pole mechanism 10. Clamp mechanism 29 is a duplicate of clamp mechanism 23. It includes a clamp bolt 31 that extends through the two halves of the split blade 22; the head of the bolt is located on the far side of the mechanism as shown in FIGS. 1, 2 and 4 and the bolt is threaded onto a clamp nut 32 mounted on the near side of blade 22. The position of nut 32 on blade 22 is determined by a set screw dog 33 that is threaded into one of a plurality of tapped holes 34 in the clamp nut. In the illustrated construction, there are six of the threaded holes 34 in nut 32, which can be aligned with any one of five different small holes 35 in blade 22. This affords a simple and convenient arrangement for indexing nut 32 to any desired position that will maintain the requisite tight clamping contact between blade 22 and end terminal 14 when the pole mechanism is closed on terminal 14, without damage to the switch.

The pivotal mounting of movable contact member 17 on the fixed center terminal 12 also comprises a center clamp means 37 for clamping the apex portion of the dual movable contact member to the center terminal. The center clamp means 37 comprises a clamping and mounting bolt 38; the head of bolt 38 is located on the near side of the mechanism as shown in FIGS. 1, 2 and 4. Bolt 38 extends through a central aperture in center terminal 12 and through both sides of the dual movable contact member 17 and is threaded into a nut 39 on the opposite side of pole mechanism 10, as shown in FIG. 3. Nut 39 is affixecl to a center clamp drive lever 41 by means of a set screw dog 42, the mounting arrangement being the same as described for nut 32. The head of bolt 38 is affixed to a similar drive lever 43 on the near side of the pole mechanism. Drive levers 41 and 43 are the terminal members of two toggle linkages described more fully hereinafter.

Pole mechanism 10 includes a single, unified actuating means 50 for moving the movable contact member 17 between its first and second contact positions, FIGS. 2 and 4 respectively. The unified actuating means 56 also actuates the clamp means 23 and 37 to a clamping condition when movable contact member 17 is thrown to its first contact position (FIG. 2). Furthermore, actuating means 50 actuates the clamping means 29 and 37 to clamping condition when contact member 17 is moved to its second contact position (FIG. 4). Actuating means 511 also serves to open the clamping means whenever contact member 17 is shifted away from either of its two contact positions.

Actuating means 56 comprises a main actuating member that includes two lever elements 51 and 52 located on op posite sides of the two halves of the movable contact member 17. The two lever elements 51 and 52 of the main actuating member arejoined by an actuating bar 53 which may be connected to the actuating lever elements of any other pole mechanisms incorporated in a complete switch with pole mechanism 10. In FIG. 3, bar 53 has been omitted. Bar 53 is secured to lugs 55 and 56 on lever elements 51 and 52, respectively. Lever elements 51 and 52. are pivotally mounted on a pin or shaft 53 that is mounted on the bight portion of the V- shaped contact member 17.

The main actuating lever 51-53 is connected to both of the blades 21 and 22 of movable contact member 17 and to all three of the clamping mechanisms 23, 29 and 37. The linkage that connects the main actuating member to blade 21 and to clamping means 23 and 37 begins with a drive link 57 that is pivotally connected to a pin 58. Link 57 has an elongated slot 59 in which a pin 61 is engaged. Pin 61 extends through the two lever elements 51 and 52 (FIG. 3).

Link 57 is paired with an auxiliary drive link 62 that is also pivotally connected to pin 58. Additional interconnection between links 57 and 62 is provided by two pins 63 and 65. The ends of links 57 and 62 opposite pin 58 are pivotally connected to a clamp drive lever 64 by pin 65. Clamp drive lever 64 is connected to the head of clamp bolt 24 to rotate the clamp bolt upon rotation of the clamp drive lever. Thus, a toggle linkage is established between the main actuating lever 51-53 and the clamp actuating lever 24, the toggle linkage including the three pivot points established by pins 61, 63 and 65, affording a rigid connection between the actuating lever lever element 51 and drive lever 64 when the three pins are aligned colinearly as indicated by the phantom line 67 in FIG. 1.

The paired drive links 57 and 62 are also a part of an additional toggle linkage. This second toggle linkage, which is partly common with the first linkage describe above, includes a link 68 that is pivotally connected at its other end to a pin 69 that is mounted upon the clamp drive lever 43 for the center clamp means 37. From FIG. 1, it can be seen that the toggle linkage comprising levers 57 and 62 and link 68 affords a rigid connection to drive lever 43 when the pivot pins 65, 58 and 69 are colinearly aligned as indicated by the phantom line 71.

A spring guide 73 is connected to the two toggle linkages described immediately above; guide 73 carries a rivet 74 that engages in a slot in drive lever 43. The other end of guide 73 has an elongated slot 75 that engages a pin 76 mounted upon blade 22 of movable contact member 17. A fixed stop member 77 is mounted upon guide 73, at the end adjacent rivet 74. A washer or other slidable stop member 78 is mounted on the opposite end of guide member 73 and a compression bias spring 79 is mounted on the guide member between stop members 77 and 78. Spring 79 normally biases the two toggle linkages comprising the drive links 57 and 62 to the toggle positions shown in FIG. 1; it also serves to bias the same toggle linkages to an alternate position, shown in FIG. 2, as described more fully hereinafter.

On the opposite side of movable contact member 17, a corresponding set of linkages is utilized to connect the main actuating member comprising lever elements 51 and 52 and bar 53 to the second end clamp means 29, the center clamp means 37, and the second blade 22. Because these toggle linkages duplicate those shown on the near side of the mechanism. they have not been illustrated in full detail. However, the main drive link 87, corresponding to drive link 57, is shown in the drawings in FIGS. 1-3. Drive link 87 is connected to the clamp drive lever 84 of the second end terminal clamp means 29 by a pin 85 (FIG. 1). Lever 87 is connected to a link 88 by a pin 98. Link 88, in turn, is connected by a pin 89 to the drive lever 41 for the center clamp means 37. Drive lever 41 is connected to a biasing spring 99 mounted on the guide 93 that is pivotally connected to the drive lever 41 by a pin 94 and to the contact blade 21 by a pin 96.

Each of the two blades 21 and 22 is also provided with a light spring-loaded biasing means, at the center of the blade, urging the two halves of the blade together to prevent momentary open circuits during actuation of the switch. For blade 22, this auxiliary biasing means comprises a pin 101 that extends through the two halves of blade 22. A small compression spring 102 is mounted upon pin 101 and exerts a continuous light biasing force urging the two halves of the split blade 22 toward each other. For blade 21, a duplicate biasing means is provided, as indicated by a pin 103.

In considering the operation of pole mechanism 10, perhaps the best starting point is the position shown in FIG. 1, with movable contact member 17 near its first contact position, a position in which a circuit is completed between terminals 12 and 13. As shown in FIG. 1, the actuating member 51-53 is locked in balanced relation to contact member 17, being centered on a line 105 bisecting the angle formed by the two blades 21 and 22 ofthe movable contact member. A rigid connection from actuating member 51-53 to blade 21 is provided by the toggle mechanism comprising drive links 57 and 62 and lever 63, the three pivot points 61, 63 and 65 being aligned along the toggle line 67. By the same token, a rigid connection is provided from the main actuating lever 51-53 to blade 22 by the corresponding linkage comprising link 37, clamp drive lever 84%, and pins 61, 85 and 95. As long as the two toggles remain unbroken, movable contact member 17 can be freely pivoted from the position shown in FIG. 1 downwardly until engagement is almost initiated with terminal 14-; throughout this complete range of movement, there is no change in any of the clamping means 23, 29 or 37. A light pressure contact is maintained with the center terminal 12, due to the auxiliary bias means 1G1, 102 and 103, but this does not interfere substantially with free pivotal movement of contact member 17.

However, if actuating lever bar 54 is pivoted through a small additional clockwise angle from the position shown in FIG. 1, the clamp drive lever 64 comes into engagement with a toggle post 113 that is mounted adjacent to terminal 13. This pivots lever 64 clockwise and breaks the toggle between clamp drive lever 64 and drive link 57, since pin 65 is driven out of alignment with pins 61 and 63. At about the same time, the sleeve 27 on bolt 24 bottoms in the slot in terminal 13. As a consequence. continuing clockwise movement of the main actuating lever 51-53 causes that lever to rotate around pin 54, so that further clockwise movement of the main actuating lever 51-53 causes link 57 and 62 to rotate clamp drive lever 64 in a clockwise direction, tightening bolt 24 in nut 25 (FIGS. 2 and 3). At the same time, the continuing clockwise movement of the main actuating lever 51-53 pulls link 68 upwardly, as seen in FIG. 2, rotating the center clamp drive lever 43 in a clockwise direction and tightening clamp bolt 38 in nut 39. Thus, when movable contact member 17 and actuating member 51-53 have been driven to the position shown in FIG. 2, the upper blade 21 of contact member 17 completes a circuit between terminals 12 and 13 and is firmly and positively clamped to both terminals.

The clockwise rotation of the clamp drive lever 43 compresses the toggle bias spring 79; compare FIG. 1 with FIG. 2. Compression spring 79, having been driven offcenter with respect to the axis of bolt 38, exerts its biasing force in a clockwise direction relative to drive levers l3 and 64 and thus urges the toggle mechanisms to remain in the closed condition shown in FIG. 2, holding both of the clamping means 23 and 37 in their clamping condition. Thus, switch pole 10 cannot be opened inadvertently by vibration or other mino. external influences.

To open pole mechanism 1 from the first contact position illustrated in FIG. 2, the actuating bar 53 is moved in a counterclockwise direction. initially, bar 53 and the related actuating lever elements 51 and 52 pivot about shaft 54; contact member 17 is firmly clamped to terminals 12 and 13 and can not pivot around its axis. As the pivotal movement of the main actuating lever 51-53 begins, a lug 115 on lever element 51 engages a cam face 116 on the main drive lever 57. This locks links 57 and 62 to lever 51 and causes the links 57 and 62 to pull clamp drive lever 64 in a counterclockwise direction. As a consequence, the end terminal clamp means 23 is released during the initial movement ofthe connecting bar 53. Furthermore, link 68 is driven downwardly, oivoting drive lever 43 in a counterclockwise direction and releasing the center clamp means 37. As soon as pin 74 is driven below a line connecting the axis of bolt 38 with the axis of pin 76, spring guide 73 passes its center point and spring 79 assists the movement of the linkages back toward the normal released position shown in FIG. 1. It can thus be seen that both of the clamping means 21 and 37 are positively driven to released condition before movable contact member 17 begins to pivot away from its first contact position.

The starting position for opening of pole mechanism 10, from its first closed position (FIG. 2), begins with the main operating lever 51-53 centered upon the line 121. The initial arcuate movement of the main operating lever, preferably about 10 to 20, returns each of the two clamping means 23 and 37 to released condition, as described above, with the main operating lever ending up in centered alignment with respect to a line 122. During this initial movement of the main lever 51-53, over the are 125, the movable contact member 17 does not move appreciably.

As soon as the main operating lever reaches alignment with line 122, however, and the two toggles connected to levers 43 and 64 are restored to their normal conditions, the continuing counterclockwise movement of the main operating lever 51-53 pivots movable contact member 17 from the position shown in FIG. 2 to that shown in FIG. 4. The movement of contact member 17 is the direct result of a corresponding arcuate movement of 90", over the are 126, by the main operating member 51-53. Thus, when movable contact member 17 first reaches its second contact position (FIG. 4), the main actuating lever 51-53 is centered on the line 123 displaced 90 from the line 122.

To complete the throwing of the pole to its second contact position, the actuating bar 53 is driven further in a counterclockwise direction, pivoting the main actuating lever 51-53 about the shaft 54 through the minor are 127 and into centered alignment with a line 124. In the early part of this movement, the clamp drive lever 84 is engaged by a toggle post 114. This breaks the toggle connections from the main actuating lever to the two clamp means 29 and 37. During the movement of the main actuating lever 51-53 over are 127, the toggle linkage connecting lever 51-53 to clamp drive lever 84 rotates the clamp drive lever through a substantial counterclockwise arc (compare FIGS. 1 and 4) and clamps the contact blade 22 to fixed terminal 14. Moreover, the linkage comprising link 88 pivots clamp drive lever 41 in a counterclockwise direction, as shown in FIG. 4, and clamps the movable contact member 17 to the center terminal 12. Toggle spring 99 biases both of the clamp means 37 and 29 to maintain the clamp means in clamping condition.

As can be seen from the drawings, and particularly FIG. 4, the path of movement for main drive lever 51-53 is a substantially smooth and continuous one. The main portion of the operating path for the main actuating lever, are 126, is a continuous segment of a circle centered about the axis of bolt 38. The two short arcs and 127 a at the ends of the path are centered about the extreme limit locations of shaft 54, but do not deviate substantially from the curvature of the main are 126. As a consequence, pole mechanism 10 operates smoothly and rapidly as movable contact 17 is driven between its two contact positions and the intermediate disconnect position.

The same operating mechanism as described above can be used with substantial variations in pole mechanism 10. For example, if it is desired to afford a make-before-break action, this can be accomplished by widening the angle of the V- shaped main contact member 17 so that it will engage one end terminal just before it clears its engagement of the other. Indeed, the V configuration of movable contact 17 can be widened simply in order to reduce the extent of the main are 126 in the travel of the movable contact in any application in which a shortened switching motion is desired.

The important of the lost motion connection afforded by pin 61 and slot 59, connecting the main drive lever element 51 to link 57, can be seen by comparing FIGS. 2 and 3, on the one hand, with FIG. 4 on the other. As movable contact member 17 reaches its second contact position, FIG, 6, toggle post 14 engages clamp drive lever 84 and breaks the toggle linkage comprising link 87 and lever 84. During the continuous movement of the main drive lever through are 127 that actuates the clamp means 29 and 37 to clamping condition, it is important that the toggle linkages on the other side of the movable contact member, comprising link 57, not be broken. This is accomplished by the provision of the lost motion connection comprising slot 59', as the final clamping movement is effected for the second contact position of contact member 17, pin 61 moves through slot 59 so that the toggle linkages comprising link 57 are not disturbed On the opposite side of the mechanism a similar lost motion means is used to preclude breaking of the toggles comprising link 87 upon actuation of the clamp means that are actuated by the toggle linkages comprising link 57.

As noted above, when the pole mechanism is to be opened from its first contact position (FIG, 2], the initial movement of bar 53 causes lug 115 on lever 51 to engage cam surface 116 on link 57. This interlock between link 57 and lever 51 assures release of clamp means 23 and 37 before any substantial leverage is applied to contact member 17 to open the switch pole. Similarly, the oppositely directed lug 117 on lever 51 engages the surface 118 on link 87, when pole mechanism ll) is to be opened from its second closed position as shown in FIG. 4. The interengagement between members H7 and lid assures release of the clamping means 29 and 37 before contact member l7 can be moved away from its second contact position, FIG. 4. The interlocks provided by members 1l5-1i8 effectively preclude relative movement between the main actuating lever 51-53 and either of the main toggle links 57 and 87, whenever the switch is to be opened, until the clamp means actuated by the affected toggle linkage has been loosened A combination are tip and blade spacer 131 is shown at the end of each of the blades 21 and 22 (FIGS. 1-4). These arc tips are included at the blade ends to keep the blades spread apart enough to assure good contact pressure without excessive blade deflections on closing. They also serve as are con tacts, connecting electrically to matching contacts ix auxiliary load interrupting devices when high load interrupting capabilities are needed. Arc contacts prevent arcing and consequent erosion of main switch contacts by closing in parallel before the main contacts close and by opening a parallel arcing circuit after the main contacts open.

I claim:

l, A pole mechanism for a double-throw pressure contact switch comprising:

a central terminal;

first and second end terminals mounted in aligned relation on opposite sides of the center terminal;

a movable contact member, comprising first and second contact blades disposed in a V configuration, havings its apex mounted on the center terminal for pivotal movement between a first contact position in which said first lade engages said first end terminal, an intermediate position range, and a second contact position in which said second blade engages said second end terminal;

first and second clamp means for positively clamping said first and second contact blades to said first and second end terminals, respectively;

center clamp means for positively clamping the apex of said movable contact member to said center terminal;

each of said clamp means being actuatable between a released condition and a clamping condition;

and unified actuating means for moving said movable contact member between its contact positions, for actuating said first clamp means and said center clamp means to clamping condition when the movable contact member is in its first contact position, and for actuating said second clamp means and said center clamp means to clamping condition when the movable contact member is in its second contact position, said actuating means comprising:

A. a main actuating member movable along a substantially continuous path between a first closed position and a second closed position to complete the full range of operations of said actuating means and hence for the pole mechanism;

B. a first toggle linkage rigidly connecting said actuating lever to said first blade and to said first and center clamp means when said movable contact member is in its intermediate position range;

C. a second toggle linkage rigidly connecting said actuating lever to said second blade and to said second and center clamp means when said movable contact member is in its intermediate position range;

D. first toggle break means for breaking the first toggle linkage, as the movable contact member approaches its first contact position, to allow said actuating member to move to its first closed position, through a limited additional distance relative to said movable contact member, and thereby actuate both said first clamp means and said center clamp means to clamped condition;

E. and second toggle break means for breaking the second toggle linkage, as the movable contact member approaches its second contact position, to allow said actuating member to move to its second closed position, through a limited additional distance relative to said movable contact member, and thereby actuate both said second clamp means and said center clamp means to clamped condition;

each of said toggle linkages including lost motion means to preclude breaking of that toggle linkage in response to the additional movement of the actuating lever allowed by breaking of the other toggle.

2, A switch pole mechanism according to claim 1 in which said actuating lever is pivotally mounted on said movable contact member at a pivot point located on a line bisecting the angle formed by the contact blades, and in which the movement of the actuating lever relative to the movable contact member, upon breaking of either toggle, is an arcuate movement of the order of 10 to 20.

3. A switch pole mechanism according to claim 1, in which the actuating lever and a main link in each toggle linkage include interlocking elements that engage when the actuating lever moves through said limited distance to actuate said clamping means, said interlocking elements precluding relative movement between the actuating lever and the main link of the toggle linkage, upon return movement of the actuating lever, until loosening of the clamp means actuated by that tog gle linkage has been effected.

4. A switch pole mechanism according to claim 1 in which the first toggle linkage includes an overcenter bias spring for biasing the first and center clamp means toward clamped condition whenever the movable contact member is in its first contact position, in which the second toggle linkage includes an overcenter bias spring for biasing the second and center clamp means toward clamped condition whenever the movable contact member is in its second contact position, and in which both said overcenter bias springs bias their respective toggle linkages toward toggle alignment whenever the mova ble contact member is intermediate its two contact positions to maintain the actuating lever at a given position intermediate said contact blades.

5. A switch pole mechanism according to claim 1 in which the movable contact member is pivotally mounted on the center terminal by a clamp bolt that extends through both the movable contact member and the center terminal and is threaded into a clamp nut, said clamp bolt and clamp nut comprising the center clamp means, the clamp bolt head and the clamp nut each being connected as a terminal element in a respective one of the toggle linkages so that for one contact position the movable contact member is clamped to the center .n-naia...

each blade is a dual blade engaging both sides of the center terminal and both sides of the associated end terminal, and further comprising a light spring-loaded biasing means, at the center of each split blade, urging the two halves of the blade together to prevent momentary open circuits during actuation of the switch. 

1. A pole mechanism for a double-throw pressure contact switch comprising: a central terminal; first and second end terminals mounted in aligned relation on opposite sides of the center terminal; a movable contact member, comprising first and second contact blades disposed in a V configuration, havings its apex mounted on the center terminal for pivotal movement between a first contact position in which said first blade engages said first end terminal, an intermediate position range, and a second contact position in which said second blade engages said second end terminal; first and second clamp means for positively clamping said first and second contact blades to said first and second end terminals, respectively; center clamp means for positively clamping the apex of said movable contact member to said center terminal; each of said clamp means being actuatable between a released condition and a clamping condition; and unified actuating means for moving said movable contact member between its contact positions, for actuating said first clamp means and said center clamp means to clamping condition when the movable contact member is in its first contact position, and for actuating said second clamp means and said center clamp means to clamping condition when the movable contact member is in its second contact position, said actuating means comprising: A. a main actuating member movable along a substantially continuous path between a first closed position and a second closed position to complete the full range of operations of said actuating means and hence for the pole mechanism; B. a first toggle linkage rigidly connecting said actuating lever to said first blade and to said first and center clamp means when said movable contact member is in its intermediate position range; C. a second toggle linkage rigidly connecting said actuating lever to said second blade and to said second and center clamp means when said movable contact member is in its intermediate position range; D. first toggle break means for breaking the first toggle linkage, as the movable contact member approaches its first contact position, to allow said actuating member to move to its first closed position, through a limited additional distance relative to said movable contact member, and thereby actuate both said first clamp means and said center clamp means to clamped condition; E. and second toggle break means for breaking the second toggle linkage, as the movable contact member approaches its second contact position, to allow said actuating member to move to its second closed position, through a limited additional distance relative to said movable contact member, and thereby actuate both said second clamp means and said center clamp means to clamped condition; each of said toggle linkages includinG lost motion means to preclude breaking of that toggle linkage in response to the additional movement of the actuating lever allowed by breaking of the other toggle.
 2. A switch pole mechanism according to claim 1 in which said actuating lever is pivotally mounted on said movable contact member at a pivot point located on a line bisecting the angle formed by the contact blades, and in which the movement of the actuating lever relative to the movable contact member, upon breaking of either toggle, is an arcuate movement of the order of 10* to 20*.
 3. A switch pole mechanism according to claim 1, in which the actuating lever and a main link in each toggle linkage include interlocking elements that engage when the actuating lever moves through said limited distance to actuate said clamping means, said interlocking elements precluding relative movement between the actuating lever and the main link of the toggle linkage, upon return movement of the actuating lever, until loosening of the clamp means actuated by that toggle linkage has been effected.
 4. A switch pole mechanism according to claim 1 in which the first toggle linkage includes an overcenter bias spring for biasing the first and center clamp means toward clamped condition whenever the movable contact member is in its first contact position, in which the second toggle linkage includes an overcenter bias spring for biasing the second and center clamp means toward clamped condition whenever the movable contact member is in its second contact position, and in which both said overcenter bias springs bias their respective toggle linkages toward toggle alignment whenever the movable contact member is intermediate its two contact positions to maintain the actuating lever at a given position intermediate said contact blades.
 5. A switch pole mechanism according to claim 1 in which the movable contact member is pivotally mounted on the center terminal by a clamp bolt that extends through both the movable contact member and the center terminal and is threaded into a clamp nut, said clamp bolt and clamp nut comprising the center clamp means, the clamp bolt head and the clamp nut each being connected as a terminal element in a respective one of the toggle linkages so that for one contact position the movable contact member is clamped to the center terminal by one toggle linkage turning the clamp bolt while the other toggle linkage holds the clamp nut and for the other contact position the movable contact member is clamped to the center terminal by one toggle linkage holding the clamp bolt while the other toggle linkage turns the clamp nut.
 6. A switch pole mechanism according to claim 1 in which the movable contact member is of split construction, so that each blade is a dual blade engaging both sides of the center terminal and both sides of the associated end terminal, and further comprising a light spring-loaded biasing means, at the center of each split blade, urging the two halves of the blade together to prevent momentary open circuits during actuation of the switch. 